The invention concerns a cutting device for tooling sandwich plates with a motor-driven cutting tool that can move in the cutting direction relative to the sandwich plate being tooled and has a cutting element moved by means of a guide mechanism in a plane of movement that runs transverse to the plane of the plate.
Sandwich plates are multilayer workpieces whose individual layers are not uniform in mechanical strength. They are generally composed of a foam core and cover layers on both sides of it in the form of thin metal sheets. Sandwich plates are typically 40 to 200 millimeters thick, and the metal sheet, which is most often steel, is approximately 1 millimeter thick.
A generic device for tooling sandwich plates is described in U.S. Pat. No. 4,984,615. The cutting tool of the known device has several cutting elements in the form of cutting knives that are arranged one after another in the cutting direction and are moved in a straight line in that direction. The leading cutting knives in the cutting direction run transverse to the plane of the plate and are inclined to one another in a V shape. A trailing cutting knife that trails the cutting knives inclined to one another is aligned perpendicular to the plane of the plate in the cutting direction. The leading cutting knife cuts a strip of material out of a cover layer of the sandwich plate, which has relatively high mechanical strength, and that way the core of the sandwich plate is cut free. Then the relatively soft core of the sandwich plate is cut through by means of the cutting knife running perpendicular to the plane of the plate.
The disadvantage of the known cutting device is that it allows sandwich plates to be tooled only from the free edge of the plate.
Starting from the state of the art described, the problem of this invention is to expand the ways of tooling sandwich plates separately so the cutting surfaces have at least uniform quality.
The invention solves this problem, in the case of the type of cutting device mentioned at the beginning, by making the cutting tool a cutting chain with cutting elements in the form of chain links and a chain guide as the guide mechanism, where the chain links, lying one after the other in their direction of movement, are moved relative to one another, so they can swivel on swivel axes running transverse to their plane of movement by means of a chain guide in the plane of movement, sometimes in a straight line, sometimes turned in a curve, and have several cutting teeth one after another in their direction of movement which project radially on the cutting chain and have cutting edges that run transverse to the plane of movement of the chain links, where the perpendicular projections of the cutting edges in the plane of movement are arranged at least partially along a line curved radially to the outside. Because of the features described, the cutting device in the invention has the option of tooling sandwich plates separately from their free edges out or starting from any point on the surface of the plates. Depending on the requirements, it is possible to make the cut go through or not go through. The part of the cutting chain in which the chain links are turned around can go into the sandwich plate to be tooled. If the cutting chain is in contact with the straight guide of the chain links, a smooth cutting front bordering the cutting slit made in the cutting direction is produced. These types of smooth cutting fronts need the peak line on the corner of the cutout where two cutting slits meet to run straight, in the corners of the cutouts on the sandwich plate in question. The design in the invention for the cutting teeth ensures that the different materials in a sandwich plate can be cut by means of the cutting device, with no hooking which would impair the quality of the cutting results. Qualitatively high cutting results are also achieved by the invention""s feature whereby the perpendicular projections on the cutting edges are arranged at least partially along a line curved radially to the outside. The curve of said line can be chosen so that all cutting edges of all chain links in the area where they are curved move on one and the same path, but in any case on approximately identical paths.
Experience has shown that good cutting results are achieved whenxe2x80x94as is provided in one preferred embodiment of the inventionxe2x80x94the radius of curvature of the line, along which the perpendicular projections of the cutting edges are arranged on the chain links in the plane of movement, is 0.8 to 2.5 times the smallest radius of curvature of the path of movement, which the perpendicular projections of the cutting edges describe in the plane of movement for the curved turn of the chain links.
Besides the precautions described already above, a number of measures have been taken on the cutting devices in the invention to guarantee good cutting results.
They can be added or used alternatively. In this sense, one variation of the invention provides that the cutting chain has three adjacent rows of chain links, where the chain links in the two outer rows form outer links and the chain links in the row in the center form center links, and where the adjacent outer links are flush with one another, and the center links are arranged staggered to the outer links in the direction of movement of the chain links and overlap with the outer links, lying one behind the other in their direction of movement and/or that the cutting edges of at least the adjacent outer links are flush with one another and/or that the outer surfaces of the chain or outer links are flat and/or that at least one of the outer surfaces of the chain links or outer links forms a free angle and runs opposite the assigned cutting surface on the sandwich plate and/or that the chain links have at least five cutting teeth respectively and/or that the cutting surfaces of at least some of the center links on the cutting chain project radially opposite the cutting edges of the outer links and/or that the distances between the cutting edges of adjacent cutting teeth on a chain link vary.
On the type of multi-row cutting chains described above, the intermediate space that remains between the cutting teeth, next to one another in the direction of movement, of two outer links following one another in said direction can be closed, if necessary, by means of the cutting teeth of the center link of the cutting chain overlapping with the outer links in question arranged in said intermediate space. Seen in the direction of movement of the cutting links, there is therefore a close sequence of cutting teeth and cutting edges. A flat design of the outer surfaces of the chain links or outer links is used for precise guidance free of unwanted shaking on the cutting surfaces of the sandwich plate being tooled in the cutting direction. The cutting chain is kept from being clamped fast to the sandwich plate,by the free angle set by the invention between the outer surface of the chain links or the outer links of the cutting chain and the cutting surface opposite said surfaces on the sandwich plate. The variation in the distances in the cutting edges of cutting teeth adjacent to one another on a chain link described above makes the cutting chain run quietly and smoothly, allows high cutting and tooling speeds and produces superior quality cutting surfaces.
If the cutting devices in the invention have several rows of cutting links, the outer and center links next to one another, for the sake of simplicity, are connected to one another with connecting bolts, whose axes form the swivel axes on which the chain links lying one behind the other in their direction of movement are able to swivel in relation to one another. Said connecting bolts preferably expand radially into a band in their axial sections assigned to the center links.
In the interest of environmental and worker protection, the cutting dust formed when tooling sandwich plates must be vacuumed up. For this purpose, in the case of one preferred design of the cutting device in the invention, the cutting chain is at least partially enclosed by a drive housing, creating an intermediate space that can be connected to a vacuum device between the cutting chain and the inside wall of the housing.
To guarantee high-quality tooling results, the cutting chain of the cutting device must move precisely in relation to the sandwich plate being tooled. For this purpose, the invention provides for a machine guide, by means of which the basic body of the cutting device, which has the cutting chain for tooling the sandwich plate in question, can be moved and guided relative to it, especially when cutting into the sandwich plate. For example, this prevents the cutting chain or chain guide from tilting when cutting into the sandwich plate.
In one preferred variation of the invention, the machine guide includes a support that can support the sandwich plate being tooled, on which the basic body of the cutting device is mounted so it can move and be guided in relation to the sandwich plate.
One variation of the cutting device in the invention is characterized by the simple kinematics of the relative movement of the basic body of the cutting device in relation to the sandwich plate, in which case the basic body of the cutting device is mounted so it can swivel on the support on an axis running parallel to the plane of the plate.
Another embodiment of the invention is characterized by the fact that the basic body of the cutting device can be moved or swiveled out of a resting position into a working position by means of the machine guide against the effect of a return force. Due to the effect of the return force, the basic body of the cutting device, and with it the cutting chain, automatically moves into a position in which the cutting chain is not in contact with the sandwich plate in question.
To make it easier to use, one preferred design of the invention provides that in the working setting, the basic body of the cutting device can be stopped and preferably locked at various positions, if necessary various swivel positions of the cutting chain and the chain guide relative to the sandwich plate in question. This way, once the right relative position of the cutting chain or chain guide and sandwich plate is set, it stays and the operator of the device does not have to do anything.
In another variation of the cutting device in the invention, there is a support for the machine guide that is designed to be structurally simple and at the same time functional which has a slide for the cutting chain that moves relative to the sandwich plate, and the chain guide.
Besides the cutting device described above, the subject of this invention is also a cutting chain for this type of cutting device. For this, the cutting chain in the invention has chain links as described in claim 19.